Tapered nut valve plug fasteners

ABSTRACT

Example tapered nut valve plug fastener apparatus disclosed herein include a valve stem, a first nut, a valve plug, and a second nut. The first nut includes a first tapered surface and the second nut includes a second tapered surface. The valve plug includes a bore. The first nut threadably engages the valve stem and the valve stem passes through the bore. The bore engages the first tapered surface. The second nut threadably engages the valve stem and the bore engages the second tapered surface.

FIELD OF THE DISCLOSURE

This disclosure relates generally to fluid valves and, moreparticularly, to tapered nut valve plug fasteners and related methods.

BACKGROUND

Conventional fluid valves include numerous valve trim componentsassembled together in a valve body. For example, a valve stem may slidein a seal of a bonnet to move an attached valve plug relative to a valveseat. The fluid valve may be open when the valve plug is moved away fromthe valve seat and may be closed when the valve plug is engaged with thevalve seat.

SUMMARY

Tapered nut valve plug fasteners are disclosed herein. In some examples,a tapered nut valve plug apparatus includes a valve stem; a first nutthreadably engaged with the valve stem, the first nut including a firsttapered surface; a valve plug having a bore, the valve stem passingthrough the bore, the bore engaging the first tapered surface; and asecond nut threadably engaged with the valve stem, the second nutincluding a second tapered surface, the bore engaging the second taperedsurface.

In some examples, a tapered nut valve apparatus includes a valve plugand a valve stem in a central passage of the valve plug, the valve plugbeing captured on the valve stem between a first tapered surface of afirst nut and a second tapered surface of a second nut.

In some examples, a tapered nut valve apparatus includes a plug having abore; a stem passing through the bore; a first tapered surface of thestem engaging the bore; and a nut opposite the first tapered surfacethreadably engaged with the stem and abutting the plug.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of an example fluid valve having anexample fastener apparatus described herein.

FIG. 2 is a detailed cross-sectional view of the example fastenerapparatus of FIG. 1.

FIG. 3 is a cross-sectional view of an alternative example fastenerapparatus that may be used in place of the example fastener apparatus ofFIGS. 1 and 2.

FIG. 4 is a cross-sectional view of a further alternative examplefastener apparatus that may be used in place of the example fastenerapparatus of FIGS. 1-3.

FIG. 5 is a cross sectional view and an enlargement of the valve stem ofthe example fastener apparatus assembly of FIG. 3.

The figures are not to scale. Wherever possible, the same referencenumbers will be used throughout the drawing(s) and accompanying writtendescription to refer to the same or like parts. As used in this patent,stating that any part (e.g., a layer, film, area, or plate) is in anyway positioned on (e.g., positioned on, located on, disposed on, orformed on, etc.) another part, means that the referenced part is eitherin contact with the other part, or that the referenced part is above theother part with one or more intermediate part(s) located therebetween.Stating that any part is in contact with another part means that thereis no intermediate part between the two parts.

DETAILED DESCRIPTION

Known fluid valves are typically designed to suit the needs ofparticular respective applications. As a result, a relatively largenumber of differently designed fluid valves exist, which necessitatesthe manufacture and inventorying of a relatively large number ofcomponents for these fluid valves. The complexity associated with themanufacturing and inventory management (e.g., part numbers andcross-references) of this relatively large number of fluid valvecomponents results in increased costs.

More specifically, many of the above-mentioned known fluid valvesinclude differently designed trim components that are only used in oneor a limited number of fluid valves. For example, there are numerousvalve stems having different diameters as well as numerous valve plugdesigns, each of which may be configured to couple to a particular valvestem via a particular fastening mechanism. Oftentimes, known valve stemshave a threaded end that threadably engages with a threaded bore in thevalve plug. As such, the thread size and count may vary widely amongsuch valve stems and valve plugs, thereby limiting the number ofdifferent valves in which each of these components can be used.

Unlike the known fluid valves mentioned above, the example fluid valvesdescribed herein employ a valve plug having a relatively large centralbore (e.g., a central passage) that can receive a relatively wide rangeof valve stem diameters. The central bore of the valve plug isunthreaded and, thus, does not directly engage the threaded end of thevalve stems. Further, the central bore of the valve plug is sized toprovide sufficient clearance between the largest diameter valve stem tobe used and the wall of the central bore to enable this largest diametervalve stem to be centralized in the bore of the valve plug despitedimensional tolerances. In the examples described herein, the threadedend of the valve stem passes through the central bore in the valve plugand a nut having a tapered surface is tightened on the threaded end ofthe valve stem such that the tapered surface engages the bore in thevalve plug to fix the valve plug to the valve stem. The tapered surfaceacts to centralize the valve stem relative to the bore in the valve plugas the nut is tightened, thereby enabling valve stems having differentdiameters to be mated to the valve plug. The tapered surface furtheracts to seal the bore to prevent process fluid leakage through the valveplug. In some examples described herein, tapered surfaces in addition tothat provided by the nut noted above may be used. For example, a secondtapered nut may be used such that each end of the central bore in thevalve plug is captured by a respective tapered nut. In another example,a portion of the valve stem may include a tapered surface that engagesthe end of the valve plug bore opposite the end at which the tapered nutis fastened. In examples described herein, the ends of the valve plugbore may include respective tapered or beveled surfaces that arecomplementary to the tapered surfaces of the nut and/or the valve stemto facilitate alignment (e.g., centralization of the stem in the plug)and increase the amount of material engagement between the valve stem,the fastening nut(s) and the valve plug. In examples described herein,the ends of the valve plug bore may include respective radiused surfacesto receive the tapered surfaces of the nut and/or the valve stem tofacilitate compatibility between the valve stem, the fastening nut(s)and the valve plug.

FIG. 1 is a cross-sectional view of an example fluid valve 112 having anexample fastener apparatus 114 described herein. In the illustratedexample of FIG. 1, the fluid valve 112 includes a valve body 116, abonnet 118, a valve seat 120, a cage 122, a valve stem 124, and a valveplug 126. The example fastener apparatus 114 includes a first nut 128and a second nut 130. The valve plug 126 includes a central bore 132.The valve stem 124 includes a threaded end 134, a smooth region 136, anda screw thread taper (not shown in FIG. 1). The screw thread taperprovides a transition between the smooth region 136 and the threaded end134. The nuts 128,130 may include respective internal threads.

In the illustrated example of FIG. 1, the second nut 130 is threadablyengaged with the valve stem 124 via the threaded end 134 and the screwthread taper, specifically the second nut 130 is tightened on thethreaded end 134 against the screw thread taper until a locking frictionis achieved between the internal threads and the threaded end 134. Thevalve stem 124 passes through the central bore 132. The second nut 130engages the central bore 132. The first nut 128 is threadably engagedwith the valve stem 124 via the threaded end 134. The first nut 128 isalso engaged with the central bore 132. Thus, the valve plug 126 iscaptured on the valve stem 124 between the first nut 128 and the secondnut 130.

FIG. 2 is a detailed cross-sectional view of the fastener apparatus 114of FIG. 1. As clearly shown in FIG. 2, the threaded end 134 of the valvestem 124 passes through the central bore 132 of the valve plug 126 andis fixed to the valve stem 124 via the first and second nuts 128, 130.In the example of FIG. 2, the first nut is 128 threadably engaged withthe threaded end 134 on the valve stem 124 adjacent an end 240 of thevalve stem 124 to engage a first aperture 242 of the central bore 132 ofthe valve plug 126. In a similar manner, the second nut 130 isthreadably engaged with the threaded end 134 on the valve stem 124 toengage a second aperture 244 of the central bore 132 of the valve plug126. Thus, the nuts 128, 130 capture the valve plug 126 on the valvestem 124 via the central bore 132. As can be seen in FIG. 2, a clearancespace 246 is provided between the valve stem 124 and an outer wall 248of the central bore 132. Additionally, the first and second nuts 128,130 include respective first and second tapered surfaces 250, 252 thatengage the apertures 242, 244 of the central bore 132. The engagement ofthe tapered surfaces 250, 252 against the apertures 242, 244 causes thevalve stem 124 to be centralized in the central bore 132 and seals thecentral bore 132 to prevent process fluid from passing through the valveplug 126. As shown in FIG. 2 the apertures 242, 244 of the central bore132 may include respective third and fourth tapered surfaces 254, 256(e.g., seats) that are complementary to the first and second taperedsurfaces 250, 252, respectively. The third and fourth tapered surfaces254, 256 may be included as shown to facilitate the centralization ofthe valve stem 124 in the central bore 132, form seals with the nuts128, 130, and/or to increase the amount of surface area engagementbetween the nuts 128, 130 and the valve plug 126. The increased surfacearea engagement provided by the third and fourth tapered surfaces 254,256 may distribute the load applied by the nuts 128, 130 to the valveplug 126 and/or may serve to prevent rotation of the valve plug 126relative to the valve stem 124 during use.

As depicted in FIG. 2, the valve plug 126 may also include a cavity 258or recess in which the first nut 128 and the end 240 of the valve stem124 are shielded from fluid flow within the valve body 116 of FIG. 1.Additionally, a weld 260 may be used to fix the first nut 128 to thevalve stem 124 to prevent the first nut 128 from rotating or looseningafter it has been tightened against the valve plug 126.

To assemble the example fastener apparatus 114 of FIG. 2, the second nut130 is threaded onto the valve stem 124, the valve stem 124 is passedthrough the central bore 132 to engage the second nut 130 with thefourth tapered surface 256, and the first nut 128 is tightened on thethreaded end 134 against the third tapered surface 254 to tension thevalve stem 124. Thus, the valve stem 124 is aligned with the centralbore 132 and centralized in the valve plug 126. In some examples, thefirst nut 128 is tightened against the third tapered surface 254 until alocking friction is achieved between the internal threads of the firstnut 128 and the threaded end 134. Further, the first nut 128 may bewelded to the valve stem 124 to form the weld 260. Thus, the valve plug126 may be permanently attached to the valve stem 124.

Additionally or alternatively, any type of anti-rotation device may beemployed to fix the first nut 128 relative to the valve stem 124 (e.g.,adhesive, a polymer lining in the first nut 128, safety wire, etc.).

FIG. 3 depicts a cross-sectional view of an alternative fastenerapparatus 314 that may be used in place of the example fastenerapparatus 114 of FIGS. 1 and 2. In the example of FIG. 3, a valve stem324 is fixed to the valve plug 126 via nuts 328, 130 having taperedsurfaces 350, 252 as in the example of FIGS. 1 and 2 described above.However, in this example, the first nut 328 is a castled nut and thevalve stem 324 includes a transverse hole 306 at an end 340 of the valvestem 324 to receive a cotter pin 308. As shown, the cotter pin 308passes through opposing recesses 310 (only one is visible in the view ofFIG. 3) in the first nut 328 and the transverse hole 306 to prevent thefirst nut 328 from rotating or loosening from the valve stem 324 afterthe first nut 328 has been tightened against the valve plug 126.

The fastener apparatus assembly 314 of FIG. 3 is assembled as in theexample of FIG. 2 described above. However, in this example, aftertightening the first nut 328 against the third tapered surface 254, thecotter pin 308 is inserted through the transverse hole 306 and therecesses 310. The cotter pin 308 may then be bent around the first nut328 and the end 340 to retain the cotter pin 308 in the transverse hole306 and the recesses 310, as shown in the example of FIG. 3. Thus, thevalve plug 126 may be removed from the valve stem 324 by removing thecotter pin 308 (e.g., during maintenance, cleaning, disassembly, partreplacement, etc.).

FIG. 4 depicts a cross-sectional view of a further alternative fastenerapparatus 414 that may be used in place of the example fastenerapparatus 114, 314 of FIGS. 1-3. In the example of FIG. 4, a valve stem424 is fixed to a valve plug 426 via the first tapered surface 250 ofthe first nut 128 and a second tapered surface 452, as in the example ofFIGS. 1-3 described above. However, in this example, the second taperedsurface 452 is included in (e.g., is integral with) the valve stem 424.Thus, the second nut 130 of FIGS. 1-3 is eliminated. In the illustratedexample of FIG. 4, the valve stem 424 also includes a threaded end 434.In the illustrated example of FIG. 4, the valve plug 426 includes acentral bore 432 and first and second radiused surfaces 454, 456. Thesecond tapered surface 452 is engaged with the second radiused surface456. The first tapered surface 250 of the first nut 128 is engaged withthe first radiused surface 454. The first and second radiused surfaces454, 456 may be included as shown to facilitate compatibility betweenthe valve stem 424, the first nut 128, and the valve plug 426. Therounded edge provided by the first and second radiused surfaces 454, 456may accommodate varying taper angles of the first and second taperedsurfaces 250, 452. Also, the first and second radiused surfaces 454, 456and the first and second tapered surfaces 250 452 may serve to seal thecentral bore 432 to prevent leakage of process fluid through the valveplug 426 and/or to centralize the valve stem 424 in the valve plug 426.Further, the valve plug 426 may be used in conjunction with the valvestems 124, 324 and the nuts 128, 130, 328 of FIGS. 1-3.

To assemble the example fastener apparatus assembly 414 of FIG. 4, thethreaded end 434 of the valve stem 424 is passed through the centralbore 432 to engage the second tapered surface 452 with the secondradiused surface 456 and the first nut 128 is tightened on the threadedend 434 against the first radiused surface 454 to tension the valve stem424. Thus, the valve plug 426 is captured on the valve stem 424 betweenthe second tapered surface 452 and the first tapered surface 250. Insome examples, the first nut 128 is tightened against the first radiusedsurface 454 until a locking friction is achieved between the internalthreads of the first nut 128 and the threaded end 434. Additionally, ananti-rotation device (e.g., the weld 260 of FIG. 2) may fix the firstnut 128 to the valve stem 424 (not shown in FIG. 4). Alternatively, thecastled first nut 328 and the cotter pin 308 of FIG. 3 may be used withthe valve stem 424 (not shown in FIG. 4). In some such examples, thevalve stem 424 includes a transverse hole to accept the cotter pin 308(not shown in FIG. 4).

FIG. 5 is a cross sectional view and an enlargement 506 of the valvestem 324 of the example fastener apparatus assembly 314 of FIG. 3. Inthe illustrated example of FIG. 5, the transverse hole 306 is morevisible. In the illustrated example of FIG. 5, the valve stem 324includes the threaded end 334 and a smooth region 536. As shown in theenlargement 506, the valve stem 424 also includes a screw thread taper512. As also shown in the enlargement, the threaded end 334 includesexternal threads 516. The screw thread taper 512 provides a transitionbetween the external threads 516 and the smooth region 536. Inoperation, the second nut 130 of FIGS. 1-3 (not pictured in FIG. 5) istightened against the screw thread taper 512 until a locking friction isachieved between the internal threads of the second nut 130 and theexternal threads 516.

From the foregoing, it will be appreciated that the above disclosedapparatus and articles of manufacture may increase interchangeabilitybetween valve stems and valve plugs. Thus, the number of part numbersand associated part management costs may be reduced. Further, the numberof valve stems and/or valve plugs held in inventory and associatedstorage costs may be reduced. Further, the assembly complexity of thevalve stem and valve plug combination and associated manufacturing costsmay be reduced.

Although certain example methods, apparatus and articles of manufacturehave been disclosed herein, the scope of coverage of this patent is notlimited thereto. On the contrary, this patent covers all methods,apparatus and articles of manufacture fairly falling within the scope ofthe claims of this patent.

1. An apparatus comprising: a valve stem; a first nut threadably engagedwith the valve stem, the first nut including a first tapered surface; avalve plug having a bore, the valve stem passing through the bore, thebore engaging the first tapered surface; and a second nut threadablyengaged with the valve stem, the second nut including a second taperedsurface, the bore engaging the second tapered surface.
 2. The apparatusof claim 1, wherein the bore of the valve plug further includes a firstaperture shaped to receive the first tapered surface and a secondaperture opposite the first aperture shaped to receive the secondtapered surface.
 3. The apparatus of claim 2, wherein at least one ofthe first aperture or the second aperture includes a tapered surface. 4.(canceled)
 5. The apparatus of claim 1, further including means forretaining the second nut on the valve stem.
 6. The apparatus of claim 5,wherein the means for retaining includes a cotter pin.
 7. The apparatusof claim 5, wherein the means for retaining is a weld.
 8. The apparatusof claim 1, wherein the second nut and an end of the valve stem aredisposed in a cavity of the valve plug.
 9. An apparatus comprising: avalve plug; and a valve stem in a central passage of the valve plug, thevalve plug being captured on the valve stem between a first taperedsurface of a first nut and a second tapered surface of a second nut. 10.The apparatus of claim 9, wherein the valve plug includes a first seatand a second seat, the first seat to engage the first tapered surface,and the second seat to engage the second tapered surface.
 11. Theapparatus of claim 10, wherein at least one of the first seat or thesecond seat includes a beveled surface.
 12. (canceled)
 13. The apparatusof claim 9, further including an anti-rotation device to retain thesecond nut on the valve stem.
 14. The apparatus of claim 13, wherein theanti-rotation device is a cotter pin inserted through the valve stem anda recess of the second nut.
 15. The apparatus of claim 13, wherein theanti-rotation device is a weld. 16-20. (canceled)
 21. The apparatus ofclaim 1, wherein the bore of the valve plug further includes a firstaperture and a second aperture opposite the first aperture, the firstaperture having a third tapered surface that is complementary to thefirst tapered surface of the first nut, the second aperture having afourth tapered surface that is complementary to the second taperedsurface of the second nut.
 22. The apparatus of claim 6, wherein thecotter pin passes through a transverse hole formed in the valve stem.23. The apparatus of claim 22, wherein the second nut is a castle nuthaving a recess shaped to receive the cotter pin.
 24. The apparatus ofclaim 9, wherein the central passage of the valve plug includes a firstaperture and a second aperture opposite the first aperture, the firstaperture having a third tapered surface that is complementary to thefirst tapered surface of the first nut, the second aperture having afourth tapered surface that is complementary to the second taperedsurface of the second nut.
 25. The apparatus of claim 14, wherein thecotter pin passes through a transverse hole formed in the valve stem.26. The apparatus of claim 25, wherein the second nut is a castle nuthaving a recess shaped to receive the cotter pin.